Since a conventional low-voltage high-current power supply is used in view of having the high current, it is required for the power supply to be provided with a circuit board having a copper-clad surface with a copper-clad area which has a corresponding size for sustaining heat produced after the high current flows therethrough and for decreasing circuit transmission loss. Accordingly, in designing the power supply, it is required to provide a large copper-clad area to be used as a space for dissipating the heat produced when the high current flows therethrough. In addition, since a tin-plated copper foil usually has a thickness of 0.0684 mm (2 oz), it is not sufficient to provide a lateral area enough for the high current to flow therethrough, which may thus lead to accumulation of heat and reduction of voltage output efficiency caused by gradually raising temperature due to increasing impedance. Furthermore, since the circuit board is provided with electronic components (e.g., transistors) on a back surface thereof and the electronic components will produce heat during operation thereof, it is also required to dissipate heat produced by the electronic components during the operation so as to prevent the operation of the electronic components from being affected by excessively high temperature.